Rdio may not be the most popular streaming music service – it has never said how many people use it – but it has always been one of the nicest to use thanks to its widely-praised design.

Now it wants to make it easier for people to discover new music. The company, which was launched in 2010 by Skype co-founders Niklas Zennstrom and Janus Friis, has bought music app startup TastemakerX for an undisclosed amount.

The latter company started life in 2012 as an iPhone app pitched as a fantasy sports-style game for music fans, who would buy virtual shares in songs, then watch the price rise or fall based on their popularity with other players. It has since also launched on Android.

The real goal was to create a network of music tipsters, with a chart of trending songs, and a gradually-deepening understanding of the tastes of those users. The game was a path towards a valuable data set, in the same way that Foursquare's system of points and mayorships helped that startup build a useful database of places and recommendations.

Over time, TastemakerX de-emphasised its game aspect in favour of a feature called Collections, which encouraged people to choose their favourite musicians, then gathered songs, music, photos and videos from various internet services for other users to browse.

Now the company is part of Rdio, with its seven-person team joining the company and its chief executive Marc Ruxin taking up a role as the streaming service's chief operating officer.

“Unlike many of the other players in the space, Rdio exists, in one way, as fiercely independent. It serves only the master of distributing a great music experience. It is not in business to sell hardware, search queries, or physical products,” said Ruxin as the deal was announced, taking a shot at Apple, Google and Amazon.

“It is my hope that over time, music discovery becomes easier, more fun and seamlessly social. Rdio really is a place for music lovers, we thrilled to begin this next voyage."

In a separate interview with PandoDaily, Ruxin said that Rdio has “millions” of users, but has chosen not to announce a detailed figure because until recently, it didn’t have a free version, so wasn’t trying to publicly talk up its growth.

By comparison, Spotify has 40m active users including 10m paying subscribers; Deezer has 16m active users including 5m paying subscribers, and Rhapsody has 1.7m paying subscribers split between its service in the US, and its Napster subsidiary elsewhere in the world.

Rdio is not the only streaming service buying startups to boost its music discovery features. Spotify bought Tunigo, a Swedish startup focused on curating playlists for streaming services, in March 2013. The effects of that deal can be seen in the themed playlists that now appear on Spotify’s homepage.

Spotify also paid a reported $100m for US big-data firm The Echo Nest in March 2014, and is using its technology to better understand the relationship between songs and artists, as well as to provide more personalised music recommendations. Rdio had been a partner of The Echo Nest too, but swiftly cut its ties following the acquisition.

Spotify, Rdio and their rivals are focusing a lot on music discovery at the moment, because they want to go mainstream. While early adopters relished the idea of unlimited access to a catalogue of more than 20m songs, the streaming companies believe a much bigger, more mainstream audience needs more help navigating through all this music.

Playlists – built by humans or computer algorithms – are a big part of this drive, but so are tastemakers, from journalists, DJs and musicians through to well-informed fans. Rdio's acquisition of TastemakerX hints at its ambitions to capitalise more on the latter group in the future.